Not that this should be the final word on the subject, but I have read that that while tea has enough active ingredients for print toning (especially cyanotypes and the like) it is not concentrated enough for development purposes. That being said, I was also told that coffee based formulae were of no possible use in print development, yet I find this works quite well with most papers. Give it a try, don't be afraid to fiddle with the formula. You just might prove that it works.